FIRE DRAMA: The driver and a handful of passengers fled a Transperth bus which burst into flames and was destroyed. Picture: Richard Polden

FIRE DRAMA: The driver and a handful of passengers fled a Transperth bus which burst into flames and was destroyed. Picture: Richard Polden

FIRE DRAMA: The driver and a handful of passengers fled a Transperth bus which burst into flames and was destroyed. Picture: Richard Polden

FIRE DRAMA: The driver and a handful of passengers fled a Transperth bus which burst into flames and was destroyed. Picture: Richard Polden

FIRE DRAMA: The driver and a handful of passengers fled a Transperth bus which burst into flames and was destroyed. Picture: Richard Polden

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Fire analysis experts from the original bus supplier, local fire investigation specialists, and engineering consultants from Australia and overseas conducted an investigation into each incident — three buses caught fire in a matter of weeks.

The Public Transport Authority (PTA) said today that the modifications had undergone testing and field trials, and would now be carried out on the entire fleet by Mercedes-Benz and bus body builder Volgren Australia.

The PTA has also agreed to drop legal action against the firms. The works will happen in segments so not all the buses would be off the road at once.